Microelectromechanical (MEM) fabrication technologies such as surface and bulk micromachining and LIGA (an acronym based on the first letters for the German words for lithography, electroplating and injection molding) have been extensively developed in recent years to form many different types of microsystems and microsensors. For certain uses, these microsystems and microsensors can include one or more permanent magnets. Current fabrication technologies result in each permanent magnet having the same magnetic pole alignment unless piece-part assembly is used to insert pre-magnetized permanent magnets into a device. What is needed is a method of forming a plurality of permanent magnets in an unmagnetized state and then magnetizing them with a predetermined north-south magnetic pole alignment.
The present invention provides an advance in the art by addressing the above need and providing a method based on thermally-assisted magnetic field switching which can be used to switch the north-south magnetic pole alignment of certain of the permanent magnets to an opposite polarity while not changing the north-south magnetic pole alignment for the remainder of the permanent magnets.
The present invention can be used to form MEM devices having an alternating north-south magnetic pole alignment for different types of applications including mechanical energy harvesting to generate electrical power, for vibration sensing, for acceleration or impact sensing, etc.
The present invention can also be used to form permanent magnet direct current (dc) motors which can be fabricated, for example, by LIGA.
These and other advantages of the present invention will become evident to those skilled in the art.